Questions swirled Sunday about what caused iconic singer Whitney Houston's sudden death, with authorities offering little information at a time when many were still struggling to come to grips with the news.

While an autopsy was complete as of late Sunday afternoon, Assistant Chief Ed Winter of the Los Angeles County Coroner's office said it could take six to eight weeks before the results are in on toxicology and other tests.

"There was no visible signs of trauma, and foul play is not suspected at this time," Winter said, adding that "the cause of death right now is deferred."

More official details on the investigation aren't expected to surface anytime soon, after the Beverly Hills, California, police department was granted a "security hold." Common in high-profile cases, this puts limits on what can be revealed about a probe.

Authorities have said that police and fire officials were called to Houston's room at the Beverly Hilton Hotel at 3:43 p.m. Saturday after her bodyguard found her unconscious body in a bathtub.

Winter, from the coroner's office, said Houston was removed from the tub before paramedics performed CPR. She was pronounced dead at 3:55 p.m.

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Pill bottles were found at the scene, entertainment news website TMZ reported, citing "informed sources." CNN could not immediately confirm the TMZ report and Winter declined to comment.

Whatever the exact cause, the grief about the death of Houston -- whose soaring voice and enormous talent were clouded in recent years by her battles with drug addiction -- was evident Sunday at the 54th annual Grammy awards show, which is typically the biggest night on the music industry's calendar.

After a performance by Bruce Springsteen, Grammy host LL Cool J began his monologue by acknowledging "we've had a death in our family" and offering a prayer thanking God "for sharing our sister Whitney with us."

"Although she's gone too soon, we remain truly blessed to have been touched by her beautiful spirit and to have her lasting legacy of music to cherish and share forever," the rapper and actor said.

Earlier, on the red carpet, Kim Burrell told CNN she'd exchanged voicemails with her good friend Houston shortly before her death, describing her as being "in great spirits, as always." She always thought of Houston as a "fighter" and a "survivor," which made the idea of her passing all the more difficult to comprehend.

"She's my sister and she'll always be my sister," said an emotional Burrell, herself a singer. "I love her dearly."

Burrell said she'd flown to California to join Houston in attending a pre-Grammy party Saturday night hosted by the songstress' longtime mentor, Clive Davis.

Houston never made it, dying at the age of 48.

Amid the outpouring of grief, Beverly Hills police said Houston's 18-year-old daughter, Bobbi Kristina, was taken to Los Angeles' Cedars-Sinai Medical Center, at about 11:15 a.m. Sunday. Details of her condition were not disclosed.

A source close to the family told CNN that by late Sunday afternoon the teenager was out of the hospital and would be heading back to New Jersey possibly as early as Sunday night. She was expected to go to the home of her grandmother, gospel singer Cissy Houston, in New Jersey, the source said.

Bobbi Kristina Brown was born during Houston's marriage to R&B singer Bobby Brown, which ended in divorce in 2007. Burrell said she was with the teenager late Saturday, admitting the girl had felt "overwhelmed" while expressing confidence that "she'll pull through."

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Her father, Bobby Brown, did not perform at a scheduled New Edition concert Sunday night in Nashville in the wake of his ex-wife's death, said Candy Lowd, a promoter for the concert.

The previous night, he was openly emotional during a concert in Southaven, Mississippi, said attendee and CNN iReporter Moshiu Knox, at one point asking people to say a prayer for his daughter, for his mother and "for me, because I'm going to need it."

"Bobby was crying during his performance and at one point had to walk off stage," Knox said.

Houston's battles with drugs had long made headlines, but she was in the midst of a comeback, with a few shows scheduled and a movie in the works.

"I did really get the sense that she was really trying to make a comeback," megachurch pastor T.D. Jakes, executive producer of Houston's upcoming movie "Sparkle," said Sunday.

"And I think that the reason that so many people are devastated is because it is not just her music, but it is her misery that attached itself to the hearts of Americans, and we watched her struggle to regain her footing after a tumultuous relationship and bouts with abuse and substance abuse.

"I think the believability of her human struggle made her song and her acting that much more powerful because we recognize that often it is the caged bird that sings," Jakes said.

A music industry executive, who recalled hearing two loud booms from the room below hers -- the room where, she later learned, Houston had died -- said she had seen Houston and Bobbi Kristina swimming in the hotel pool days before.

The two looked happy, she recalled, and Houston seemed healthy and beautiful. However, it remained unknown whether the singer had won her battle with substance abuse for good.

Houston had performed as late as Thursday night at a pre-Grammy event in the area, singing a raspy rendition of "Jesus Loves Me" with singer Kelly Price.

Houston's family said in a statement Sunday, "We are devastated by the loss of our beloved Whitney. This is an unimaginable tragedy and we will miss her terribly. We appreciate the outpouring of love and support from her fans and friends."

Her fans remembered her in her prime on Sunday, when she reigned as pop queen during the 1980s, selling some 170 million albums, singles and videos.

"Perhaps now Whitney can rest in everlasting life without the harsh judgment that she felt in this world," said CNN iReporters Kimberly and Betty Kiel from Pearland, Texas.

And in the church where Houston grew up, the New Hope Baptist Church in Newark, New Jersey, members gathered to honor her.

As a young girl, Houston grew sang solos in the choir at the church. Her mother served as director of sacred music at the church for 54 years and is still a member there.

Whitney Houston was born in Newark in 1963 and was soloing in the junior choir by age 11, according to the All Music Guide. "Whitney's mother and cousins nurtured her passion for gospel music since birth," according to Houston's official website. Her cousins include singers Dee Dee Warwick and Dionne Warwick, and her godmother was Aretha Franklin.

Franklin told CNN on Sunday that the news of her goddaughter's death is "almost unbelievable."

"It's stunning, absolutely stunning," the iconic performer said. "I could not believe what I was reading ... It's a sad day, a very sad day."

The Rev. Jesse Jackson was among those attending the service in Newark.

"Whitney is a winner," he told reporters outside the church. "Her singing, her inspiring people around the world, it's been a great source of joy and uplift. And so we grieve, and yet we rejoice even in our grieving."

Jackson said he spoke to Cissy Houston on Saturday night and Sunday morning and headed to her home after the service.

"They're having to process this," he said of Houston's family. "This was not some long, debilitating sickness. This was sudden. And so when this happens, there's no rational explanation, just you have to cling to your faith and hold on until the morning comes."